Regulator for calutron ion source



Aug. 2, 1955 B. F. MILLER REGULATOR FOR CALUTRON ION SOURCE 4 Sheets-Sheet l Filed July 5, 1945 INVENTOR. Buffa/7 F Mil/er BY Q@ mm v@ m@ N@ E Ow mm R ow Aug. 2, 1955 B. F. MILLER REGULATOR FOR CALUTRON ION SOURCE Filed July 5, 1945 Aug. 2, 1955 B. F. MILLER REGULATOR ROR OALUTRON ION SOURCE 4 Sheets-Sheet 3 Erl/79 i Filed July 5, 1945 POLYPI-IASE A. C. POWER SUPPLY Aug. 2, 1955 B. F. MILLER 2,714,666

REGULATOR FOR CALUTRON ION SOURCE Filed July 5, 1945 4 Sheets-Sheet 4 F l E INVENTOR. 5w? To/v F/W/LLER United States vPatent Ollie 2,714,666 REGULATR FR CALUTRON 10N SURCE Burton F. Miller, Berkeley, Calif., assignor to the United States of America as represented by the United States Atomic Energy Commission Application `luly 5, 1945, Serial No. 603,399 14 Claims. (Cl. Z50-41.9)

This invention relates to improvements in electric discharge devices, and more particularly to calutrons ot' the type disclosed in the copending applications of Ernest O. Lawrence, Serial No. 557,784, tiled October 9, 1944, and Serial No. 536,40l, led May 19, 1944.

A calutron is a device for increasing the proportion of a selected isotope in an element containing a plufor deionizing and collecting the ions of the selected isotope thus concentrated, thereby to produce a deposit of the element enriched with the selected isotope.

The apparatus is especially useful in producing uranium enriched with U235.

In the previously-mentioned copending application, Serial No. 536,401, there is disclosed a calutron of the multiple beam type, including, as shown in Figures 24, 25, and 26 thereof, an ion source unit provided with an arc block having a number of arc chambers formed therein. In this source unit, each arc chamber is provided with electron emitting structure individual thereto which is utilized to ionize the vapor contained in the associated arc chamber.

Likewise, the instant application pertains to a ca1ut tron of the multiple beam type including an ion source unit provided with a plurality of arc blocks, each having one or more arc chambers formed therein. In this source unit, however, the electron emitting devices are provided with power supplies common to all of them, together with circuits adapted to regulating each individual are. In another aspect, the conductors to two or more electron emitting devices may be combined electrically in such manner as to reduce the total number of heavy electrical conductors.

One object of this invention is to provide, in a calu- `tron ion source unit, an improved cathode circuit and arc regulator arrangement.

Another object of the invention is to provide a regulated calutron multiple ion source unit requiring a reduced number of electrical conductors connected thereto.

Another object of the invention is to provide a calutron ion source apparatus employing a plurality of independently regulated ion generators.

Another object of the invention is to provide a calutron ion source unit including a plurality of cathodes lllfotili Patented Ang. 2, li

with an improved arrangement for controlling the emissions thereof.

Another object of the invention is to provide a calutron ion source unit with an improved circuit for regulating the arc current by utilizing a saturable reactor.

Further objects of the invention will appear from a reading of the following detailed description ot' apparatus embodying the invention.

In the accompanying drawings, forming part of the specification,

Figure l is a diagrammatic plan View of a calutron comprising an improved ion source employing a plurality of independently regulated ion generators;

Fig. 2 is a vertical sectional view of the calutron taken along the line 2-2 of Fig. l;

Fig. 3 is a schematic wiring diagram of the ion source tilament supply, arc supply and regulator incorporated in the calutron shown in Fig. l;

Fig. 4 is a schematic wiring diagram of an alternate ion source filament supply, rc supply and regulator adapted to a calutron having a limited number of arcs, and

Pig. 5 is a wiring diagram of the embodiment of the invention shown in Figs. l and 3 and including circuits of a single ion generator for the purpose of simplifying the explanation of the operation of that embodiment. to Figs. l and 2, there structure, including upper and lower pole pieces 11 and 12 provided with substantially parallel spaced-apart pole faces, and a tank 13 disposed between the pole faces of the pole pieces 11 relatively strong magnetic eld therebetween, which magnetic iield passes through the tank 13 and the various parts housed therein. The tank 13 is of tubular con figuration, being substantially arcuate in plan, and comthe tank 13, whereby the interior of the tank 13 may be evacuated to a pressure of the order of 105 to l0*4 mm. Hg. Preferably, the component parts of the tank 13 are formed of steel, the top and bottom walls: 14 and 15 thereof being spaced a short distance from the pole faces i of the upper and lower pole pieces 11 and 12 respectively,

the tank 13 being retained in such position in any suitable manner, whereby the top and bottom walls 14 and 1S constitute in effect pole pieces with respect to the interior of the tank 13, as explained more fully hereinafter.

The removable end wall 18 suitably supports ion source units 21 and 22 provided with charge receptacles 23 and Z4, respectively. Two communicating arc blocks 25 and 26 are provided to the ion source unit 21 and likewise two communicating arc blocks current supply, whereby the charge receptacle 23 may be appropriately heated, the charge receptacle 23 being formed of stainless steel or the like. Likewise electric heater 3i) is arranged in heat exchange relationship with charge receptacle 24. The arc blocks 25, 26, 27 and 28 are formed, at least partially, of brass or the like and have upstanding slots 3l, 32, 33 and 34 formed in the front walls thereof remote from the charge receptacles 23 and 24. Thus, the arc blocks 25, 26, 27 and 28 are of hollow construction, the cavities in arc blocks 25 and 26 communicating with the interior of the charge receptacle 23 and the cavities in arc blocks 2.7 and 2S communicating with the interior o the charge receptacle 24.

Also, the removable end wall 18 carries four filamentary cathodes 35, 36, 37 and 3S, each in series with its respective resistance element 39, 46, 4l or 42, and adapted to be connected through busses A and B to a suitable source of iilament current supply. Alternating current is utilized to heat the cathodes andin this respect it is to be noted that the term A. C. is taken to mean alternating current and D. C. is taken to mean direct current in the remainder of the disclosure and in the appended claims. The series resistance elements 39, 40,

41 and 42 have electrical characteristics similar to those "f of the lamentary cathodes 3S, 36, 37 and 38. Each lamentary cathode 3S, 36, 37 and 38 overhangs the upper end of its respective arc block 25, 26, 27 and 28, and is arranged in alignment with respect to the upper end of the cavity formed therein. Each arc block 25, 26, 27 and 28 carries an anode 43, 44, 45 or 46, respectively, disposed adjacent the lower end thereof and arranged in alignment with respect to the cavity formed therein.

Also, each arc block 25, 26, 27 and 28 carries a collimating electrode 47, 48, 49 or 50, respectively, adjacent the upper end thereof, each having an elongated collimating slot Sl, 52, 53 or 54, respectively, formed therethrough and arranged in alignment with the electron emitting portions ot the respective one of the iilamentary cathodes 35, 36, 37 or 38, as well as with the respective one of the anodes 43, 44, 45 or 46, and the respective one of the cavities formed in the arc blocks 25, 26, 27 or 28. The anodes 43, 44, 45 and 46 and the collimating electrodes 47, 48, 49 and Sil are electrically connected to terminals l, l, H and G, respectively, of the arc supply and regulator apparatus 55. The positive terminal, K, of the arc supply and regulator apparatus 55 is associated with the positive terminal of a suitable source of accelerating electrode supply, as explained more fully hereinafter. On the other hand, the tank 13 is grounded. Also, the filament busses A and B are adapted to be operatively connected to the negative terminal of a suitable source of arc voltage supply 56, as shown in Fig. 3 and described more fully hereinafter.

Further, the removable end wall 18 carries an ion accelerating structure 57, formed at least partially of tungsten or the like, and disposed in spaced-apart relation with respect to the wall of the arc blocks 25, 26, 27 and 28 in which the slots 3l, 32, 33 and 34 are formed. The source of accelerating electrode supply is adapted to be connected between the ion sources 21 and 22 and the ion accelerating structure 57, the positive and negative terminals of the supply mentioned being respectively connected to the ion sources 21 and 22 and to the ion accelerating structure 57. Further, the negative terminal of the ion accelerating electrode supply is grounded.

The removable end wail i9 suitably supports an ion collector assembly 5S formed of stainless steel or the like, and provided with pairs of laterally spaced-apart cavities or pockets 59, oil, 6l, 62, 63, 64, 65 and 66 which respectively communicate with pairs of aligned slots 67, 68, 6%, 70, 7l, 72, 73 and 74 formed in the iront wall ot the ion collector assembly 5S disposed remote `from the removable end wall i9. lt is noted that the pockets 59, 6l, 63 and o5 are adapted to receive one ot the constituent isotopes of an element, and the pockets 60, 62, 64 and o6 another o the constituent isotopes, which have been separated in the calutron lil, as explained more ully hereinafter. Finally, the ion collector assemlit) bly 5S is electrically' connected to the ion accelerating structure 57 and the grounded terminal of the accelerating electrode supply. Thus it will be understood that the ion source units 2i and 22 are connected to the positive ungrounded terminal ot the accelerating electrode supply; while the tank i3, the ion accelerating structure 57 and the collector assembly 58 are connected to the negative grounded terminal of the accelerating electrode supply; the ion source units 2i. and 22 being electrically insulated 'from the component parts of the tanl: 13. Thus the portion oi the tank i3 disposed between the ion accelerating structure S7 and the ion collector assembly 5S constitutes an electrostatic shield for the high velocity ions traversing the curved paths between the slits 7S, 76, 77 and 7 S formed iu the ion accelerating structure 57 and the slots o7, i o9, 78, 7l., 72, 73 and 74 formed in the ion collector" assembly 5S, as explained more fully hereinafter.

Considering now the general principle of operation of the calutron iii), a charge comprising a compound of the element to be treated is placed in the charge receptacles 23 and Z4, compound of the element mentioned being one which may be readily vaporized. The end walls 18 and 19 are securely attached to the open ends of the tank i3, whereby the tanl-z i3 is hermetically sealed. The various electrical connections are completed and operation ot the vacuum pumping apparatus 2b associated with the tank 13 is initiated. When a pressure of the order of lO-5 to 4 mm. Hg is established within the tank 13, the electric circuits for the windings, not shown, associated with the pole pieces l and 't2 are energized and adiusted, whereby a predetermined magnetic held is established therebetween traversing the tanl; 13. The electric circuits for the heaters 29 and 30 are energized, whereby the charge in the charge receptacles 23 and 24 is heated and vaporized. The vapor nils the charge receptacles 23 and 24 and is conducted into the communicating cavities formed in the arc blocks 25, 26, 27 and 28. The polyphase A. C. power supply circuits are energized, whereby busses A and B are energized and the tilamentary cathodes 35, 35, 37 and 38 are heated and rendered electron emissive. Then the are voltage supply 56 causes an arc discharge to strike between the electron emitting portions or" filamcntary cathodes 3:7, 36, 37 and 38 and their respective anodes 43, 44, 45 and (i6, with electron streams proceeding from the electron emitting portions of the larnentar.' cathodes 35, 35, 37 and 353, through the collimating slots 5l, 52, 53 and 54, respectively, formed in the collimating electrodes 47, 4S, 49 and 50, respectively, to the anodes 43, 44, 45 and 46, respectively. These electron streams may be controlled in intensity by means of the arc supply and regulator 55 andV its con"- trols as described hereinafter. The collimating slotsk 5l, 52, 53 and 54 formed in the collimating electrodes 47, 4S, i9 and 50, respectively, deline the cross sections of the streams of electrons proceeding into the arc bloclts 25, 26, 27 and 28, respectively, whereby each arc discharge has a ribbon-like configuration and breaks up the molecular form of the compound of the vapor to a considerable extent, producing positive ions of the element that is to be enriched with the selected one of its isotopes.

The electric circuit between the arc blocks 25, 26, 27 and 23 and the ion accelerating structure 57 is completed, the ion accelerating structure 57 being at a high negative potential with respect to the arc blocks 2S, 26, 27' and 28, whereby the positive ions in the arc blocks 25, 26, 27 and 25 are attracted by the ion accelerating strueture57 and accelerated through the voltage impressed therebetween. More particularly, the positive ions proceed from the cavities formed in the are blocks 25, 26, 27 and 2S through the slots 3l, 32, 33 and 34forrned inthe walls thereof, and across the space between the ion accelerating structure 57 and the adjacent walls of the arc blocks 25, 26, 27 and 23, and thence through the slits 75, 76, 77 and 78, respectively, formed in the ion accelerating structure 57. The high velocity positive ions form four vertical upstanding ribbons or beams proceed ing from the cavities formed in the arc blocks 25, 26, 27 and 28 through the four slots 31, 32, 33 and 34, respectively, and the four aligned slits 75, 76, 77 and 78, respectively.

As previously noted, the ion collector assembly 58, as well as the tank 13, is electrically connected to the ion accelerating structure 57, whereby there is an electric-tield-free path for the high velocity positive ions dis posed between the ion accelerating structure 57 and the ion collector assembly 58 within the tank 13. The high velocity positive ions are deected from their normal straight-line path and from a vertical plane passing through the slots 31, 32, 33` and 34 and the aligned slits 75, 76, 77 and 78, respectively, due to the effect of the consequently of the` isotopes of Thus, ions of the relatively light isotope of the element describe interior arcs of relatively through the slots 63, 70, 72 and 74 into pockets 60, 62, 64 and 66, respectively, formed in the ion collector assembly 58. Accordingly, the ions of the relatively light isotope of the element are collected in the pockets 59, 61, 63 and 65 and are de-ionized to produce a deposit of therein.

After all of the charge in the charge receptacles 23 and 24 has been vaporized, all of the electric circuits are interrupted and the end wall 18 is removed so that After a suitable number of charges have been vaporized in order to obtain appropriate deposits of the isotopes of the element in the pockets 59, 60, 61, 62, 63, 64, 65 and 66 of the ion collector assembly 58, the end wall 19 is removed and the deposits of the collected isotopes in the pockets 59, 60, 61, 62, 63, 64, 65 and 66 in the ion vaporized and the molecular form of the vapor may be readly broken up to form positive ions of uranium. ln this case, uranium enriched with U235 is collected in the pockets 59, 61, 63 and 65 of the ion collector assembly 58, and uranium comprising principally U38 is collected in the pockets 60, 62, 64 and 66 of the ion collector assembly 58. Also, it is noted that from a practical standpoint, the deposit of uranium collected in the pockets 59, 61, 63 and 65 of the ion collector assembly 58 j the uranium deposited 1n the pockets 59, 61, 63 and 65 of the ion collector assembly 58 is considerably enriched, both with respect to U234 and U235, and considerably'impoverished with respect to Um, as compared with natural or normal uranium.

Referring now to Fig. 3, the filament supply, arc supply and regulator 55 is shown together with the filament busses A and B and the terminals C, D, E, F, G, H, I, I

A and B.

of a plurality of rectiiers 36, 87, 88 and S9; each of which in turn is connected through the D. C. winding of a plurality of saturable reactors 96, 91, 92 and 93 respectively to the terminals G, H, I, and li respectively. Thus it is seen that any current which ows from the arc voltage supply 56 to the anodes 43, 44, and 45 and 46 of the calutron 10 must pass through either the arc current control rheostats 81, 82, 83 and 84, respectively, or must pass through the bias voltage supply 85 and the rectitiers S6, 87, 88 and 89, respectively, and the D. C. windings of the saturable reactors 90, 91, 92 and 93 respectively.

It is to be observed that the polarity of the bias voltage supply 85 is such as to prevent any current from owing through the rectiers 86, 87, 88 and 89 unless a suicient voltage appears between terminal K and terminals G, H, I and J, respectively, to overcome the potential of the bias supply 85. Should no current ow through rectitiers 86, 87, 88 and 89, then no current will flow through the D. C. windings of the saturable reactors 90, 91, 92 and 93, and the A. C. windings of saturable reactors `90, 91, 92 and 93 will have their maximum impedance. Under such conditions the voltage induced in. the secondary of transformer 79 it lagging phase relationship developed in the A. C. windings of saturable reactors 90, 91, 92 and 93 as hereinafter described. Such an electrical phase relationship may be obtained from two-phase input power whereby the voltage on the secondary of transformer 80 will lead the voltage on the secondary of transformer 79 by ninety electrical degrees. Again, if three-phase input power is supplied, then the voltage on the secondary of transformer 80 will lead the voltage on the secondary oftransformer 79 by one hundred and twenty electrical degrees.

The purpose of the filament supply, arc supply and regulator 55 is to produce and to regulate a plurality of electrical arc discharges between the thermally emissive portions of the lamentary cathodes 35, 36, 37 and 38 and their respective anodes 43, 44, 45 and 46. The purpose of these electrical arc discharges has already been described; this application deals with a method for regulating the current in each such electrical arc discharge.

Consider, for example, the ion generator comprising filamentary cathode 35, collimating electrode 47, and anode 43, as shown in Fig. 5. Collimating electrode 47 and anode 43 are electrically connected together and in turn are connected to terminal J. Any are current which ows as a cathode 35 to the collimating electrode 47 or to the anode 43 must also ow through the arc current control rheostat S4 or its parallel circuit including the D. C. winding of saturable reactor 93, the rectiier 89, and the bias supply 85 as previously described. Now if the value ofy this arc discharge current is sufficiently low, theA voltage drop developed across the arc current control rheostat 84 will be insucient to overcome the bias voltage produced by the bias voltage supply 8S so that no current can flow through the D. C. winding of the saturable reactor 93 and the rectifier 89 in series. Under such conditions the impedance of the A. C. winding. or the saturable reactor 93 will be a maximum and a minimum of current will flow through this A. C. winding.

Further, under such conditions the currents flowing.

through the lamentary cathode 35 and its series resistor 39 will be essentially equal, since a minimum of current is being drawn through terminal F which leads to the junction between iilamentary cathode 35 and series resistor 39. It is to a secondary voltage across busses A and B which appears across iilarnentary cathode 35 and its series resistor 39 in series. Further, because of the phase relationships developed by the secondary voltage of transformer 80 and the inductive reactance of the saturable reactor 93, any current which ows through terminal F will be approximately in phase with the current tlowing in bus A, thereby tending to reduceV the current owing in the tilarnentary cathode 35 to a value below the current flowing in the series resistor ,3-

39. However, as previously described, when no current is flowing through rectier 89, no current will be ilowing through the D. C. winding of saturable reactor 93, the impedance of the A. C. windings of saturable reactor 93 will be. a maximum, will `be a minimum, and therefore the current owing through the filamentary cathode 35 will be a maximum. `Under such conditions the tilamentary cathode 35 will be heated to its maximum temperature by the current passing through it and will produce the maximum of,v thermally emitted electrons. These electrons will be attracted by the positive potentials of the eollimating electrode 47 and the anode 43, which positive potential is produced by the are voltage supply 56, and an electric arc discharge will result. Below a certain value of are current, all of the arc current will pass through the arc current control rheostat 84, since the bias voltage supply 85 and the rectier 89 combined to prevent any current from tlowing through the D. C. winding of the saturable reactor 93 in the parallel circuit to the arc current control rheostat 84. However, when the arc current through terminal. l reaches a predetermined value as determined by the setting of the arc current control rheostat84, then the voltage drop developed across the arc current control rheostat S4 will exceed the result of the electron emission of 5':

be noted that transformer 79 producesv .1.,

A. C. windings of the current through terminal F 'j voltage of the bias voltage supply 8S and current will begin to flow through the D. C. winding ofthe saturable reactor 93. As the current through the D. C. winding of saturable reactor 93 increases, the impedance of the A. C. winding of the saturable reactor 93 will decrease, thus allowing more A. C. current to iiow through terminal F, causing less of the A.V C. current flowing through series resistor 39 to ow through the ilamentary cathode 35. This in turn will tend to reduce the thermal emission of lamentary cathode 35, and tend to reduce the arc current ilowing through terminal J. Under such conditions a regulatory action is produced; that is, should for any reason the arc current rise above its desired predetermined value, the current through the tilamentary cathode 35 would be reduced, thereby reducing its thermal emission and tending to maintain the arc current at its predetermined value. ln such a circuit, relatively small currents ilowing through terminal F with respect to the current flowing through the series resistor 39 can produce realtively large changes in the thermalemission of lamentary cathode 35 Thus, the conductor to terminal F will need to carry far less than the current in the iilamentary cathode 35 which must be suppliedV from busses A and B.

lt is to be noted that this arc discharge occurs in a region of concentrated magnetic iield. For this reason, essentially all of the arc current flows between the lamentary cathode 3S and the collimating electrode 47r or between the filamentary cathode 35 and the anode 43. Essentially no arc current can ilow between the filamentary cathode 35 and the arc block 25 because of the direction of this concentrated magnetic eld.

The remaining circuits utilizing lamentary cathodes 36, 37 and 38 operate in exactly the same manner with the arc current controls 83, 82 and S1 respectively serving to determine the current in the arc discharge of each ion generator in the same manner as previously described.

All of the conductors previously described as connecting terminals of the filament supply, arc supply and regulator 55 to electrodes within the calutron tank 13 must of necessity pass through the walls of the calutron tank 13 at some point. Using these circuits as described, only two heavy current conductors, busses A and B, need to pass through the walls of the calutron tank 13, whereas all of the other conductors are relatively small current conductors. Thus, any number of ion generators could be utilized with only two heavy current conductors required. Further, although all of the ion generators obtain their power from common sources, it is possible to control the current of each arc discharge independently.

it is to be understood that the principles of the circuit shown in Fig. 3 can be applied not only to the calutron shown in Figs. l and 2, but also to other caultrons having various electrical and mechanical differences. Specifically, the circuit shown in Fig. 3 is not to be limited to any particular number of ion sources, such asthe two ion source units 21 and 22, or to any particular number of` iilamentary cathodes and anodes, such as the four filainentary cathodes 35, 36, 37 and 3% and their four respective anodes 43, 44, 45 and 46, shown on Figs. l and 2. Rather, the advantages of the circuit shown on Fig. 3 are more marked with an increased number of regulated arcs.

Similarly, the circuit shown in Fig. 3 is not adversely aitected by changes in the ion accelerating structure or in the accelerating electrode supply potentials. For example, the ion source units 21 and 22 could be operated at a grounded positive potential, with respect to the ion accelerating structure 57 and the ion collector assembly 58 operated ata negative ungrounded potential.

Referring now to Fig. 4, an alternate electrical circuit is shown which is particularly advantageous tor calutrons wherein a limited number of ion generators are to be utilized. The calutron ion generator 100 includes filamentary cathode 161 and anode 102, arranged in a concentrated magnetic eld. Although calutron ion generator 100 shows schematically only two electrodes, filamentary cathode 101 and anode 102, it is to be understood that Fig. 4 refers to these certain portions of a complete calutron generally similar to that one shown on Figs. l and 2. Voltage for the iilamentary cathode 101 is obtained from the secondary of transformer 103. Primary voltage for transformer 103 is obtained from a suitable A. C. power source through the A. C. windings of saturable reactor 104.

The anode 102 connects both to the D. C. control Winding of the saturable reactor 104 and to the arc current control rheostat 105 in parallel and thence to the positive terminal of a suitable arc voltage supply 106. The negative terminal of the arc voltage supply 106 is connected to the secondary of transformer 103.

The saturable reactor 104 also is equipped with a D. C. bias winding which is connected to a bias current supply 107 through a bias current control rheostat 103. The combination of bias current supply 107 and bias current control rheostat 108 serves to produce the desired bias current through the D. C. bias winding of the saturable reactor 104 and this current is of such magnitude as to produce a high degree of saturation in the core of the reactor 104.

The effect of this bias current is such as to reduce the impedance of the A. C. winding of the saturable reactor 104 to a desired low value. Thus, when the A. C. power supply is connected and current flows through the A. C. Winding of saturable reactor 104 and through the primary winding of transformer 103 in series, there will be a relatively loW voltage drop in the A. C. winding of the satura ble reactor 104 because of the relatively low impedance in the A. C. Winding of saturable reactor 104, provided that no current ows in the D. C. control winding of saturable reactor 104. This relatively large current flowing in the primary of transformer 103 will produce a relatively large voltage on the secondary of transformer 103 and will heat the iilamentary cathode 101 to its thermally emissive temperature. The arc voltage supply 106 causes the anode 102 to assume a positive potential with respect to the ilamentary cathode 101. Under suitable conditions an arc discharge in a concentrated magnetic iield will then occur between ilamentary cathode 101 and anode 102.

Any arc current which flows in the circuit of the anode 102 must l'low either through the D. C. control winding of the saturable reactor 104 or through the arc current control rheostat 105. Depending upon the setting of the are current control rheostat 105, a larger or a smaller portion of the arc current will iiow through the D. C. control winding of the saturable reactor 104.

The arrangement of the windings on the saturable reactor 104 is such that any increase in arc current through the D. C. control winding of saturable reactor 104 will produce a ilux which will buck the flux produced by the D. C. bias winding of saturable reactor 104 and will thereby tend to reduce the net D. C. llux through the core of the saturable reactor 104. When the current through the reactor D. C. control winding sets up a magnetomotive force sucient to reduce the continuous flux through the reactor core below the threshold of saturation the impedance of the A. C. winding of the saturable reactor will increase thereby reducing the current through the lamentary cathode 101.

Thus, with an increase of arc current the impedance in series with the primary of transformer 103 will be increased and the secondary voltage of transformer 103 will be decreased, reducing the temperature of lilamentary cathode 101, reducing its thermal emission, and tending to return the arc current to its previous value. The amount of arc current can be determined by the setting of the arc current control rheostat 105. In other words, this circuit produces a regulatory eiect which 10 tends to maintain the arc current constant at a prede termined Value.

It is to be understood that the circuit shown in Fig. 4 is to be preferred for one or a limited number of regulated arcs, while the circuit shown on Fig. 3 is to be preferred for a larger number of regulated arcs.

While there has been described what is at present considered to be the two preferred embodiments of the invention, it will be further understood that various modications may be made therein, and it is intended to cover in the appended claims all such modifications as fall within the true spirit and scope of the invention.

What is claimed is:

l. A regulator for a calutron ion source comprising in combination an ion source having an anode and a cathode, a resistor connected in series with said cathode, a pair of primary feeders for supplying heating current to said cathode through said resistor, a variable impedance device connected to the common terminal between said resistor and said cathode, a current supply connected in series with said variable impedance device across said cathode, said variable impedance device including control means connected between said anode and cathode and responsive to the current therebetween for controlling the impedance of said Variable impedance device to maintain the arc current through said ion source substantially constant.

2. A regulator for a calutron ion source comprising in combination an ion source having an anode and a cathode, a resistor connected in series with said cathode, a pair of primary feeders for supplying heating current to said cathode through said resistor, a variable impedance device connected to the common terminal between said resistor and said cathode, a current supply connected across said cathode in series with said variable impedance device, means for producing a magnetic eld aligned between said cathode and anode, and means responsive to the current between said anode and cathode for controlling the impedance of said variable impedance device to maintain the arc current through said ion source substantially constant.

3. A regulator for a calutron ion source comprising in combination an ion source having an anode and a cathode, wall structure for defining an arc chamber between said anode and said cathode, said arc chamber having an atmosphere to be ionized therein, a resistor connected in series with said cathode, a pair of primary feeders for supplying heating current to said cathode through said resistor, a variable impedance device connected to the common terminal between said resistor and said cathode, a current supply connected in series with said variable impedance device across said cathode, and means responsive to the current between said anode and cathode for controlling the impedance of said variable impedance device to maintain the arc current through said ion source substantially constant.

4. A regulator for a calutron ion source comprising in combination an ion source having an anode and a cathode, wall structure for defining an arc chamber between said anode and said cathode, said arc chamber having an atmosphere to be ionized therein, a resistor connected in series with said cathode, a pair of primary feeders for supplying heating current to said cathode through said resistor, a variable impedance device connected to the common terminal between said resistor and said cathode, a power supply connected in series with said variable impedance device across said cathode, means for producing a magnetic eld aligned between said cathode and anode, and means responsive to the current between said anode and cathode for controlling the impedance of said variable impedance device to maintain the arc current through said ion source substantially constant.

5. A regulator for a calutron ion source comprising in combination an ion source having an anode and a cathode, a resistor connected in series with said cathode.

a pair of primary feeders connected to said cathode through said resistor,a variable impedance device connected to the common terminal between said resistor and said cathode and to the opposite side of said cathode, a source of current supply for said cathode connected to said pair of primary feeders, and means responsive to the current between said anode and cathode for controlling the impedance of said variable impedance device to maintain the arc current through said ion source substantially constant.

6. A regulator for a calutron ion source comprising in combination an ion source having an anode and a cathode, means for producing a magnetic field through said ion source parallel to the path between said anode and cathode, said ion source having an atmosphere to be ionized therein, a resistor, a pair of primary feeders for supplying heating current to said cathode through said resistor, a variable impedance device having an A. C. primary winding and a D. C. control winding, a current source connected through variable impedance device across said cathode, and a source of arc current supply connected in series with said variable impedance control winding between said anode and said cathode thereby maintaining the arc current through said ion source substantially constant, said magnetic ield substantially confining said arc current in an elongated zone in said ion source between said anode'and said cathode.

7. A regulator for a calutron ion source comprising in combination an ion source having an anode and ra cathode, a source of heating current connected to said cathode, a resistor connected in series between said heating current source and said cathode, a source of arc current supply connected between said cathode and said anode, a saturable reactor an A. C. winding, said A. C. winding being connected from the resistor-cathode iuncture to the opposite side of said cathode to control the heating current of said cathode over a predetermined range of values, said D. C. winding being connected in series with said arc current supply source, whereby the aforesaid arc current is maintained substantially constant through regulation of said cathode heating current.

8. A regulator for a calutron ion source comprising in combination an ion source having an anode and' a cathode, means for producing a magnetic tield aligned between said cathode and said anode, a resistor, a source of heating current connected to said cathode through said resistor, a source of arc current supply connected between said cathode and said anode, a saturable reactor having a D. C. winding and an A. C. winding, said A. C. winding being connected across said cathode to control the heating current of said cathode over a predetermined range of values, said D. C. winding being connected'in series with said arc current supply source. whereby the aforesaid arc current is maintained substantially constant through regulation of said cathode heating current.

9. A regulator for a calutron ion source comprising in combination an ion source having an anode and a cathode, wall structure for deiining an arc chamber between said anode and said cathode, said arc chamber having an atmosphere to be ionized therein, a source of heating current connected to said cathode, a source of arc current supply connected between said cathode and said anode, a saturable reactor having a D. C. winding and an A. C. winding, said A. C. winding being connected across said cathode to control the heating current of said cathode over a predetermined range of values, said D. C. winding being connected in series with said source of arc current supply, and an adjustable impedance connected across said D. C. winding for maintaining said D. C. winding responsive to a predetermined portion of the current between said anode and cathode, whereby the aforesaid arc current is maintained substantially constant through regulation of said cathode heating current.

the primary winding of said having a D. C. Winding and f l0. A'regulator for a calutron ion source comprising in combination an ion source having an anode and a cathode, a source of heating current connected to said cathode, a source of arc current supply connected between said cathode and said anode, a saturable reactor having a D. C. winding, a D. C. bias winding and an A. C. winding, a regulated source of unidirectional potential connected across said bias winding, said A. C. winding being connected in series between said heating current source andv said cathode to control the heating current of said cathode over a predetermined range of values, said D. C. winding being connected in series with said source of arc current supply, whereby the aforesaid arc current is maintained substantially constant through regulation of said cathode heating current.

ll. A regulator for a calutron ion source comprising in combination an ion source having an anode and a cathode, a resistor, a pair of primary feeders for supplying alternating heating current to said cathode through said resistor from one phase of a polyphase supply, a saturable reactor having a D. C. winding and an A. C. Winding, one terminal of said A. C. winding beingxconnected to the common terminal of said cathode and said resistor and the other terminal of said A. C. winding being connected in series with another phase of said polyphase supply to the other side of said cathode, and arc current supply, a second resistor, said second resistor being connected in series with said anode and the positive terminal of said arc current supply, the negative terminal of said arc current supply being connected to said cathode, a rectifier, a D. C. bias voltage supply connected in opposition to the polarity of said rectifier, said bias voltage supply and said rectifier and said D. C. winding being connected in series across said second resistor so that the arc current passing through said second resistor operates to control the heating current throughr said saturable reactor after said arc current reaches a value such that the voltage drop across said second resistor approximates the value of said D. C. bias voltage.

12. A regulator for a calutron ion source comprising in combination an ion source having an anode and a cathode, means for producing a magnetic field aligned between said cathode and said anode, a resistor, a pair of primary feeders for supplying alternating heating current to said cathode through said resistor from one phase of a polyphase supply, a saturable reactor having a D. C. Winding and an A. C. winding, said A. C. winding being connected in series with another phase of said polyphase supply between the common terminal of said cathode and resistor and the other side of said cathode, an arc current supply, a second resistor, said second resistor being connected in series with said anode and the positive terminal of said arc current supply, the negative terminal of said arc current supply being connected to said cathode, a rectifier, a D. C. bias voltage supply connected in opposition to the polarity of said rectifier, said bias voltage supply and said rectifier and said D. C. winding being connected in series across said second resistor so that the arc current passing through said second resistor operates to control the alternating heating current through said saturable reactor after said arc current reaches a value such that the voltage drop across said second resistor approximates the value of said D. C. bias voltage.

13. A regulator for a calutron ion source comprising in combination an ion source having an anode and a cathode, wall structure for defining an arc chamber between said anode and said cathode, said arc chamber having an atmosphere to be ionized therein, a resistor, a pair of primary feeders for supplying alternating heating current to said cathode through said resistor from one phase of a polyphase supply, a saturable reactor having a D. C; winding and an A. C. winding, one terminal of said A. C. winding being connected to the common terminal of said cathode and said resistor and the otheriterrninal of said A. C. winding being connected through another phase of said polyphase supply to the other side of said cathode, an arc current supply, a second resistor, said second resistor being connected in series with said anode and the positive terminal of said arc current supply, the negative terminal of said arc current supply being connected to said cathode, a rectifier, a D. C. bias voltage supply connected in opposition to the polarity of said rectifier, said bias voltage supply and said rectifier and said D. C. winding being connected in series across said second resistor so that the arc current passing through said second resistor operates to control the current through said saturable reactor after said are current reaches a value such that the voltage drop across said second resistor approximates the value of said D. C. bias voltage.

14. A regulator for an ion source comprising in cornbination an ion source having an anode and a cathode, means establishing a magnetic eld through said ion source parallel to the path between said cathode and anode, said ion source containing an atmosphere to be ionized, an arc current circuit connected between said anode and cathode and including a source of unidirectional potential maintaining an arc discharge between said cathode and anode, a primary current source for supplying heating current to said cathode, a secondary current source, and a variable impedance connected across said cathode in series with said secondary current source, said variable impedance having control means integral therewith governed by the current of said arc current circuit to regulate the heating of said cathode in response to the magnitude of said arc discharge.

References Cited in the le of this patent UNITED STATES PATENTS 1,961,703 Morrison June 5, 1934 2,001,567 Case May 14, 1935 2,221,467 Bleakney Nov. 12, 1940 2,236,195 McKesson Mar. 25, 1941 2,331,189 Hippie Oct. 5, 1943 2,374,205 Hoskins Apr. 24, 1945 

1. A REGULAR FOR A CALUTRON ION SOURCE COMPRISING IN COMBINATION AN ION SOURCE HAVING AN ANODE AND A CATHODE, A RESISTOR CONNECTED IN SERIES WITH SAID CATHODE, A PAIR OF PRAIMARY FEEDERS FOR SUPPLYING HEATING CURRENT TO SAID CATHODE THROUGH SAID RESISTOR, A VARIABLE IMPEDANCE DEVICE CONNECTED TO THE COMMON TERMINAL BETWEEN SAID RESISTOR AND SAID CATHODE, A CURRENT SUPPLY CONNECTED IN SERIES WITH SAID VARIABLE IMPEDANCE DEVICE INCLUDING CONTROL CATHODE, SAID VARIABLE IMPEDANCE DEVICE INCLUDING CONTROL MEANS CONNECTED BETWEEN SAID ANODE AND CATHODE AND RESPONSIVE TO THE CURRENT THEREBETWEEN FOR CONTROLLING THE IMPEDANCE OF SAID VARIABLE IMPEDANCE DEVICE TO MAINTAIN THE ARC CURRENT THROUGH SAID ION SOURCE SUBSTANTIALLY CONSTANT. 